Coumarin-azasugar-benzyl conjugates as non-neurotoxic dual inhibitors of butyrylcholinesterase and cancer cell growth

We have applied the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to prepare a library of ten coumarin-azasugar-benzyl conjugates and two phthalimide-azasugar-benzyl conjugates with potential anti-Alzheimer and anti-cancer properties. The compounds were evaluated as cholinesterase inhibitors, demonstrating a general preference, of up to 676-fold, for the inhibition of butyrylcholinesterase (BuChE) over acetylcholinesterase (AChE). Nine of the compounds behaved as stronger BuChE inhibitors than galantamine, one of the few drugs in clinical use against Alzheimer's disease. The most potent BuChE inhibitor (IC50 = 74 nM) was found to exhibit dual activities, as it also showed high activity (GI50 = 5.6 ± 1.1 μM) for inhibiting the growth of WiDr (colon cancer cells). In vitro studies on this dual-activity compound on Cerebellar Granule Neurons (CGNs) demonstrated that it displays no neurotoxicity.

Dissipation, residues, and evaluation of processing factor for spirotetramat and its formed metabolites during kiwifruit growing, storing, and processing

Spirotetramat is widely used around the world to control sucking pests and may form in agricultural products. In the current study, the dissipation, residues, and evaluation of processing factor (PF) for spirotetramat and its formed metabolites were investigated during kiwifruit growing, storing, and processing. The residue analysis method was established based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with a QuEChERS method to detect the residues of spirotetramat and its metabolites in kiwifruit and its processed products. The method provided recoveries of 74.7-108.7%, and the relative standard deviations (RSDs) were 0.6-13.1%. The LOQs of spirotetramat and its four metabolites were 1 μg kg-1. The degradation of spirotetramat was best fitted for the first-order kinetics model with a half-life of 9.90-10.34 days in the field and 24.75-30.13 days during storage. Residues of spirotetramat and its formed metabolites in kiwifruit would not pose dietary risk to consumers. Moreover, the peeling and fermentation were the highest removal efficiency for the spirotetramat and its formed metabolite residues during processing. The PF values calculated after each individual process were < 1, indicating a significant reduction of residues in different processing processes of kiwifruit. The spirotetramat was degraded during kiwifruit wine-making process with half-lives of 3.36-4.91 days. B-enol and B-keto were the main metabolites detected in kiwifruit and its processed products. This study revealed the residues of spirotetramat and its formed metabolites in kiwifruit growing, storing, and processing, which helps provide reasonable data for studying the dietary risk factors of kiwifruits and products.

Synthesis, Characterization, Antimicrobial and Antimalarial Activities of Azines Based Schiff Bases and their Pd(II) Complexes

Herein, we report synthesis, characterization, antimicrobial and antimalarial activities of azines Schiff base ligands (L1 -L4 ) and their palladium (II) complexes (C1 -C4 ) of [Pd(L)(OAc)2 ] type. The azine ligands (L1 -L4 ) were prepared by condensation of carbonyl compounds with hydrazine hydrate and their complexes by the reaction of palladium acetate with L1 -L4 ligands in 1 : 1 molar ratio. The prepared ligands and their complexes were characterized by spectral characterization using 1 H &13 C-NMR, FT-IR and mass spectral studies, which revealed that the ligands coordinates via azomethine nitrogen and heteroatom or aryl carbon with palladium. Moreover, Schiff bases and their palladium (II) complexes have been screened for their antibacterial (S. aureus, B. subtillis, and S. typhi, P. aeruginosa), antifungal (C. albicans, A. niger, and A. clavatus) and antimalarial (P. falciparum) activities. The Schiff base L4 showed good results for antibacterial against S. aureus (MIC, 50 μg/mL) and antimalarial against P. falciparum (IC50 , 0.83 μg/mL). The complex C1 showed best antibacterial activity (MIC, 62.5 μg/mL) against S. typhi and the complex C4 exhibited remarkable antimalarial activity (IC50 , 0.42 μg/mL) among the tested compounds. Thus, azines based ligands and their Pd complexes can be good antimicrobial and antimalarial agents if explored further.

Design, synthesis, and antitumor study of a series of novel 1-Oxa-4-azaspironenone derivatives

A series of 1-oxa-4-azaspiro[4,5]deca-6,9-diene-3,8-dione derivatives containing structural fragments of conjugated dienone have been synthesized previously by our group, however the Michael addition reaction between conjugated dienone and nucleophilic groups in the body may generate harmful and adverse effects. To reduce harmful side effects, the authors started with p-aminophenol to make 1-oxo-4- azaspirodecanedione derivatives, then utilized the Michael addition and cyclopropanation to eliminate α, β unsaturated olefinic bond and lower the Michael reactivity of the compounds in vivo for optimization. At the same time, heteroatoms are put into the molecules in order to improve the hydrophilicity of the molecules and the binding sites of the molecules and the target molecules, establishing the groundwork for improved antitumor activity. The majority of the compounds had moderate to potent activity against A549 human lung cancer cells, MDA-MB-231 breast cancer cells, and Hela human cervical cancer cells. Among them, the compound 6d showed the strongest effect on A549 cell line with IC50 of 0.26 μM; the compound 8d showed the strongest cytotoxicity on MDA-MB-231 cell line with IC50 of 0.10 μM; and the compound 6b showed the strongest activity on Hela cell line with IC50 of 0.18 μM.

The Rise of 1,4-BN-Heteroarenes: Synthesis, Properties, and Applications

BN-heteroarenes, which employ both boron and nitrogen in aromatic hydrocarbons, have gained great attention in the fields of organic chemistry and materials science. Nevertheless, the extensive studies on BN-heteroarenes are largely limited to 1,2-azaborine-based compounds with B-N covalent bonds, whereas 1,3- and 1,4-BN-heteroarenes are relatively rare due to their greater challenge in the synthesis. Recently, significant progresses have been achieved in the synthesis and applications of BN-heteroarenes featuring 1,4-azaborines, especially driven by their significant potential as multiresonant thermally activated delayed fluorescence (MR-TADF) materials. Therefore, it is timely to review these advances from the chemistry perspective. This review summarizes the synthetic methods and recent achievements of 1,4-azaborine-based BN-heteroarenes and discusses their unique properties and potential applications of this emerging class of materials, highlighting the value of 1,4-BN-heteroarenes beyond MR-TADF materials. It is hoped that this review would stimulate the conversation and cooperation between chemists who are interested in azaborine chemistry and materials scientists working in the fields of organic optoelectronics, metal catalysis, and carbon-based nanoscience etc.

Synthesis and Luminescent Properties of s-Tetrazine Derivatives Conjugated with the 4H-1,2,4-Triazole Ring

New derivatives obtained by the combination of unique 1,2,4,5-tetrazine and 4H-1,2,4-triazole rings have great application potential in many fields. Therefore, two synthetic few-step methodologies, which make use of commercially available 4-cyanobenzoic acid (method A) and ethyl diazoacetate (method B), were applied to produce two groups of the aforementioned heterocyclic conjugates. In both cases, the target compounds were obtained in various combinations, by introducing electron-donating or electron-withdrawing substituents into the terminal rings, together with aromatic or aliphatic substituents on the triazole nitrogen atom. Synthesis of such designed systems made it possible to analyze the influence of individual elements of the structure on the reaction course, as well as the absorption and emission properties. The structure of all products was confirmed by conventional spectroscopic methods, and their luminescent properties were also determined.

Discovery of novel 2,8-diazaspiro[4.5]decan-1-one derivatives as potent RIPK1 kinase inhibitors

Necroptosis, a key form of programmed lytic cell death, has gained recognition as an important driver in various inflammatory diseases. Inhibition of kinase activity of receptor interaction protein kinase 1 (RIPK1), which block the activation of the necroptosis pathway has shown therapeutic potential in many human diseases. In order to find new chemotypes of RIPK1 inhibitors, a virtual screening workflow was performed and led to the discovery of 8-benzoyl-3-benzyl-1,3,8-triazaspiro[4.5]decane-2,4-dione (compound 8) as a hit compound. Further structural optimization identified a series of 2,8-diazaspiro[4.5]decan-1-one derivatives as potent RIPK1 inhibitors. Among them, compound 41 exhibited prominent inhibitory activity against RIPK1 with an IC50 value of 92 nM. Meanwhile, compound 41 showed a significant anti-necroptotic effect in a necroptosis model in U937 cells. Therefore, compound 41 could be employed as a lead compound of RIPK1 inhibitors for further structural optimization.

N-methylated diazabicyclo[3.2.2]nonane substituted triterpenoic acids are excellent, hyperbolic and selective inhibitors for butyrylcholinesterase

Triterpenoic acids (oleanolic, ursolic, betulinic, platanic and glycyrrhetinic acid) were acetylated and coupled with 1,3- or 1,4-diazabicyclo[3.2.2]nonanes to yield amides. Reaction of these amides with methyl iodide at the distal nitrogen of the bicyclic system gave the corresponding quaternary ammonium salts. These compounds were shown to act as excellent inhibitors of the enzyme butyrylcholinesterase (BChE) while being only weak inhibitors for acetylcholinesterase (AChE). Evaluation of the enzyme kinetics revealed these compounds to act as hyperbolic inhibitors for BChE while the results from molecular modeling gave an explanation for their selectivity between AChE and BChE.

Near-infrared emitting fluorescent homobimetallic gold(I) complexes displaying promising in vitro and in vivo therapeutic properties

Three near-infrared (NIR-I) optical theranostic systems were synthesized, characterized and studied in vitro and in vivo. These original homo-bimetallic gold(I)-based aza-BODIPY complexes proved to be trackable through near-infrared optical imaging in cells and in mice. They display anti-proliferative properties in micromolar range against human and murine cancer cell lines (4T1, MDA-MB-231, CT26, and SW480). Moreover, the injection of the most promising theranostic agent in CT26 tumor-bearing BALB/c mice induced a significant anti-cancer activity.

Mechanochemical Aza-Vinylogous Povarov Reactions for the Synthesis of Highly Functionalized 1,2,3,4-Tetrahydroquinolines and 1,2,3,4-Tetrahydro-1,5-Naphthyridines

The aza-vinylogous Povarov reaction between aromatic amines, α-ketoaldehydes or α-formylesters and α,β-unsaturated dimethylhydrazones was carried out in a sequential three-component fashion under mechanochemical conditions. Following extensive optimization work, the reaction was performed on a vibratory ball mill operating at 20 Hz and using zirconium oxide balls and milling jar, and afforded 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydro- 1,5-naphthyridines functionalized at C-2, C-4 and also at C-6, in the latter case. This protocol generally afforded the target compounds in good to excellent yields and diastereoselectivities. A comparison of representative examples with the results obtained under conventional conditions revealed that the mechanochemical protocol affords faster Povarov reactions in comparable yields using a solvent-less environment.

Improving small molecule force fields by identifying and characterizing small molecules with inconsistent parameters

Many molecular simulation methods use force fields to help model and simulate molecules and their behavior in various environments. Force fields are sets of functions and parameters used to calculate the potential energy of a chemical system as a function of the atomic coordinates. Despite the widespread use of force fields, their inadequacies are often thought to contribute to systematic errors in molecular simulations. Furthermore, different force fields tend to give varying results on the same systems with the same simulation settings. Here, we present a pipeline for comparing the geometries of small molecule conformers. We aimed to identify molecules or chemistries that are particularly informative for future force field development because they display inconsistencies between force fields. We applied our pipeline to a subset of the eMolecules database, and highlighted molecules that appear to be parameterized inconsistently across different force fields. We then identified over-represented functional groups in these molecule sets. The molecules and moieties identified by this pipeline may be particularly helpful for future force field parameterization.

New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2'-Bis(aminomethyl)-1,1'-binaphthyl

As a candidate for bifunctional asymmetric catalysts containing a half-sandwich C–N chelating Ir(III) framework (azairidacycle), a dinuclear Ir complex with an axially chiral linkage is newly designed. An expedient synthesis of chiral 2,2′-bis(aminomethyl)-1,1′-binaphthyl (1) from 1,1-bi-2-naphthol (BINOL) was accomplished by a three-step process involving nickel-catalyzed cyanation and subsequent reduction with Raney-Ni and KBH₄. The reaction of (S)-1 with an equimolar amount of [IrCl₂Cp*]₂ (Cp* = η⁵–C₅(CH₃)₅) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (5) through the double C–H bond cleavage, as confirmed by ¹H NMR spectroscopy. A loss of the central chirality on the Ir centers of 5 was demonstrated by treatment with KOC(CH₃)₃ to generate the corresponding 16e amidoiridium complex 6. The following hydrogen transfer from 2-propanol to 6 provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium 5 can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH₃)₃ in 2-propanol, leading to (S)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%.

Selective N1/N4 1,4-Cycloaddition of 1,2,4,5-Tetrazines Enabled by Solvent Hydrogen Bonding

An unprecedented 1,4-cycloaddition (vs 3,6-cycloaddition) of 1,2,4,5-tetrazines is described with preformed or in situ generated aryl-conjugated enamines promoted by the solvent hydrogen bonding of hexafluoroisopropanol (HFIP) that is conducted under mild reaction conditions (0.1 M HFIP, 25 °C, 12 h). The reaction constitutes a formal [4 + 2] cycloaddition across the two nitrogen atoms (N1/N4) of the 1,2,4,5-tetrazine followed by a formal retro [4 + 2] cycloaddition loss of a nitrile and aromatization to generate a 1,2,4-triazine derivative. The factors that impact the remarkable change in the reaction mode, optimization of reaction parameters, the scope and simplification of its implementation through in situ enamine generation from aldehydes and ketones, the reaction scope for 3,6-bis(thiomethyl)-1,2,4,5-tetrazine, a survey of participating 1,2,4,5-tetrazines, and key mechanistic insights into this reaction are detailed. Given its simplicity and breath, the study establishes a novel method for the simple and efficient one-step synthesis of 1,2,4-triazines under mild conditions from readily accessible starting materials. Whereas alternative protic solvents (e.g., MeOH vs HFIP) provide products of the conventional 3,6-cycoladdition, the enhanced hydrogen bonding capability of HFIP uniquely results in promotion of the unprecedented formal 1,4-cycloaddition. As such, the studies represent an example of not just an enhancement in the rate or efficiency of a heterocyclic azadiene cycloaddition by hydrogen bonding catalysis but also the first to alter the mode (N1/N4 vs C3/C6) of cycloaddition.

The chromatographic behaviour of new double-labelled oligodeoxynucleotide probes containing azaphthalocyanine dye as a quencher with respect to evaluation of their purity

The influence of experimental conditions on chromatographic behaviour of promising oligodeoxynucleotide double-labelled molecular probes containing an azaphthalocyanine macrocycle as a perspective dark quencher was studied. A recently introduced new stationary phase based on styrene-divinylbenzene copolymer was tested. The planar and hydrophobic structure of the azaphthalocyanine is considerably different from those of currently used fluorophores and quenchers. Thus, the most challenging issue was the separation of the double-labelled probe from its main impurity represented by a mono-labelled probe, containing only the azaphthalocyanine macrocycle. The absorbance measurement cannot simply determine this impurity, and its presence fundamentally compromises the biological assay. The commonly used gradient elution was not suitable and isocratic conditions seemed to be more appropriate. The azaphthalocyanine moiety influences the properties of the modified oligodeoxynucleotides substantially, and thus their chromatographic behaviour was determined predominantly by this quencher. Acetonitrile was the preferred organic solvent for the analysis of probes containing the azaphthalocyanine quencher and the effect of ion-pairing reagents was dependent on the probe structure. The temperature seemed to be an effective parameter for fine-tuning of the separation and mass transfer improvement. Generally, our findings could be helpful in method development for purity evaluation of double-labelled oligodeoxynucleotide probes and semipreparative methods.

Crystal structure of Leishmania mexicana cysteine protease B in complex with a high-affinity azadipeptide nitrile inhibitor

Leishmania mexicana is an obligate intracellular protozoan parasite that causes the cutaneous form of leishmaniasis affecting South America and Mexico. The cysteine protease LmCPB is essential for the virulence of the parasite and therefore, it is an appealing target for antiparasitic therapy. A library of nitrile-based cysteine protease inhibitors was screened against LmCPB to develop a treatment of cutaneous leishmaniasis. Several compounds are sufficiently high-affinity LmCPB inhibitors to serve both as starting points for drug discovery projects and as probes for target validation. A 1.4 Å X ray crystal structure, the first to be reported for LmCPB, was determined for the complex of this enzyme covalently bound to an azadipeptide nitrile ligand. Mapping the structure-activity relationships for LmCPB inhibition revealed superadditive effects for two pairs of structural transformations. Therefore, this work advances our understanding of azadipeptidyl and dipeptidyl nitrile structure-activity relationships for LmCPB structure-based inhibitor design. We also tested the same series of inhibitors on related cysteine proteases cathepsin L and Trypanosoma cruzi cruzain. The modulation of these mammalian and protozoan proteases represents a new framework for targeting papain-like cysteine proteases.

Revisiting dithiadiaza macrocyclic chelators for copper-64 PET imaging

Synthesis and characterisation of a dithiadiaza chelator NSNS2A, as well as copper complexes thereof are reported in this paper. Solution structures of copper(i/ii) complexes were calculated using density functional theory (DFT) and validated by both NMR and EPR spectroscopy. DFT calculations revealed a switch in the orientation of tetragonal distortion upon protonation, which might be responsible for poor stability of the Cu(II)NSNS2A complex in aqueous media, whilst the same switch in tetragonal distortion was experimentally observed by changing the solvent. The chelator was radiolabeled with 64Cu and evaluated using PET/MRI in rats. Despite a favorable redox potential to stabilize the cuprous state in vivo, the 64Cu(II)NSNS2A complex showed suboptimal stability compared to its tetraazamacrocyclic analogue, 64Cu(TE2A), with a significant 64Cu uptake in the liver.

Click-Chemistry (CuAAC) Trimerization of an αv β6 Integrin Targeting Ga-68-Peptide: Enhanced Contrast for in-Vivo PET Imaging of Human Lung Adenocarcinoma Xenografts

αv β6 Integrin is an epithelial transmembrane protein that recognizes latency-associated peptide (LAP) and primarily activates transforming growth factor beta (TGF-β). It is overexpressed in carcinomas (most notably, pancreatic) and other conditions associated with αv β6 integrin-dependent TGF-β dysregulation, such as fibrosis. We have designed a trimeric Ga-68-labeled TRAP conjugate of the αv β6 -specific cyclic pentapeptide SDM17 (cyclo[RGD-Chg-E]-CONH2 ) to enhance αv β6 integrin affinity as well as target-specific in-vivo uptake. Ga-68-TRAP(SDM17)3 showed a 28-fold higher αv β6 affinity than the corresponding monomer Ga-68-NOTA-SDM17 (IC50 of 0.26 vs. 7.4 nM, respectively), a 13-fold higher IC50 -based selectivity over the related integrin αv β8 (factors of 662 vs. 49), and a threefold higher tumor uptake (2.1 vs. 0.66 %ID/g) in biodistribution experiments with H2009 tumor-bearing SCID mice. The remarkably high tumor/organ ratios (tumor-to-blood 11.2; -to-liver 8.7; -to-pancreas 29.7) enabled high-contrast tumor delineation in PET images. We conclude that Ga-68-TRAP(SDM17)3 holds promise for improved clinical PET diagnostics of carcinomas and fibrosis.

Antimicrobial Activity of Gemini Surfactants with Azapolymethylene Spacer

A series of 21 azapolymethylene gemini surfactants were obtained. The synthesis of the title surfactants in one- or two-step reaction proceeds with good yields. The structure and the purity of the synthesized compounds were determined by ¹H and ¹³C NMR, ESI-MS spectra, and elemental analysis. Moreover, 2D COSY, HMBC, and HSQC spectra were performed. The minimal inhibitory concentrations (MIC) of the synthesized compounds were determined against fungi: Candida albicans, Aspergillus niger, Penicillium chrysogenum and bacteria: Escherichia coli,Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. Also, the critical micelle concentrations (CMC) were determined. The relationship between antimicrobial and surface activity and surfactant structure has been determined.

Tuning of Molecular Electrostatic Potential Enables Efficient Charge Transport in Crystalline Azaacenes: A Computational Study

The chemical versatility of organic semiconductors provides nearly unlimited opportunities for tuning their electronic properties. However, despite decades of research, the relationship between molecular structure, molecular packing and charge mobility in these materials remains poorly understood. This reduces the search for high-mobility organic semiconductors to the inefficient trial-and-error approach. For clarifying the abovementioned relationship, investigations of the effect of small changes in the chemical structure on organic semiconductor properties are particularly important. In this study, we computationally address the impact of the substitution of C-H atom pairs by nitrogen atoms (N-substitution) on the molecular properties, molecular packing and charge mobility of crystalline oligoacenes. We observe that besides decreasing frontier molecular orbital levels, N-substitution dramatically alters molecular electrostatic potential, yielding pronounced electron-rich and electron-deficient areas. These changes in the molecular electrostatic potential strengthen face-to-face and edge-to-edge interactions in the corresponding crystals and result in the crossover from the herringbone packing motif to π-stacking. When the electron-rich and electron-deficient areas are large, sharply defined and, probably, have a certain symmetry, calculated charge mobility increases up to 3-4 cm2V-1s-1. The results obtained highlight the potential of azaacenes for application in organic electronic devices and are expected to facilitate the rational design of organic semiconductors for the steady improvement of organic electronics.

C-H/C-C Functionalization Approach to N-Fused Heterocycles from Saturated Azacycles

Herein we report the synthesis of substituted indolizidines and related N-fused bicycles from simple saturated cyclic amines through sequential C-H and C-C bond functionalizations. Inspired by the Norrish-Yang Type II reaction, C-H functionalization of azacycles is achieved by forming α-hydroxy-β-lactams from precursor α-ketoamide derivatives under mild, visible light conditions. Selective cleavage of the distal C(sp2)-C(sp3) bond in α-hydroxy-β-lactams using a Rh-complex leads to α-acyl intermediates which undergo sequential Rh-catalyzed decarbonylation, 1,4-addition to an electrophile, and aldol cyclization, to afford N-fused bicycles including indolizidines. Computational studies provide mechanistic insight into the observed positional selectivity of C-C cleavage, which depends strongly on the groups bound to Rh trans to the phosphine ligand.

Superelectrophiles: Recent Advances

Superelectrophiles are reactive species that often carry multiple positive charges. They have been useful in numerous synthetic methods and they often exhibit highly unusual reactivities. Recent advances in superelectrophile chemistry are discussed in this review.

Synthesis and evaluation of new 1-oxa-8-azaspiro[4.5]decane derivatives as candidate radioligands for sigma-1 receptors

We report the design, synthesis, and evaluation of a series of 1-oxa-8-azaspiro[4.5]decane and 1,5-dioxa-9-azaspiro[5.5]undecane derivatives as selective σ1 receptor ligands. All seven ligands exhibited nanomolar affinity for σ1 receptors (Ki(σ1) = 0.47 - 12.1 nM) and moderate selectivity over σ2 receptors (Ki(σ2)/ Ki(σ1) = 2 - 44). Compound 8, with the best selectivity among these ligands, was selected for radiolabeling and further evaluation. Radioligand [18F]8 was prepared via nucleophilic 18F-substitution of the corresponding tosylate precursor, with an overall isolated radiochemical yield of 12-35%, a radiochemical purity of greater than 99%, and molar activity of 94 - 121 GBq/μmol. Biodistribution studies of [18F]8 in mice demonstrated high initial brain uptake at 2 min. Pretreatment with SA4503 resulted in significantly reduced brain-to-blood ratio (70% - 75% at 30 min). Ex vivo autoradiography in ICR mice demonstrated high accumulation of the radiotracer in σ1 receptor-rich brain areas. These findings suggest that [18F]8 could be a lead compound for further structural modifications to develop potential brain imaging agents for σ1 receptors.

Selective DYRK1A Inhibitor for the Treatment of Type 1 Diabetes: Discovery of 6-Azaindole Derivative GNF2133

Autoimmune deficiency and destruction in either β-cell mass or function can cause insufficient insulin levels and, as a result, hyperglycemia and diabetes. Thus, promoting β-cell proliferation could be one approach toward diabetes intervention. In this report we describe the discovery of a potent and selective DYRK1A inhibitor GNF2133, which was identified through optimization of a 6-azaindole screening hit. In vitro, GNF2133 is able to proliferate both rodent and human β-cells. In vivo, GNF2133 demonstrated significant dose-dependent glucose disposal capacity and insulin secretion in response to glucose-potentiated arginine-induced insulin secretion (GPAIS) challenge in rat insulin promoter and diphtheria toxin A (RIP-DTA) mice. The work described here provides new avenues to disease altering therapeutic interventions in the treatment of type 1 diabetes (T1D).

Trans-Cyclooctene-Functionalized PeptoBrushes with Improved Reaction Kinetics of the Tetrazine Ligation for Pretargeted Nuclear Imaging

Tumor targeting using agents with slow pharmacokinetics represents a major challenge in nuclear imaging and targeted radionuclide therapy as they most often result in low imaging contrast and high radiation dose to healthy tissue. To address this challenge, we developed a polymer-based targeting agent that can be used for pretargeted imaging and thus separates tumor accumulation from the imaging step in time. The developed targeting agent is based on polypeptide-graft-polypeptoid polymers (PeptoBrushes) functionalized with trans-cyclooctene (TCO). The complementary ¹¹¹In-labeled imaging agent is a 1,2,4,5-tetrazine derivative, which can react with aforementioned TCO-modified PeptoBrushes in a rapid bioorthogonal ligation. A high degree of TCO loading (up to 30%) was achieved, without altering the physicochemical properties of the polymeric nanoparticle. The highest degree of TCO loading resulted in significantly increased reaction rates (77-fold enhancement) compared to those with small molecule TCO moieties when using lipophilic tetrazines. Based on computer simulations, we hypothesize that this increase is a result of hydrophobic effects and significant rearrangements within the polymer framework, in which hydrophobic patches of TCO moieties are formed. These patches attract lipophilic tetrazines, leading to increased reaction rates in the bioorthogonal ligation. The most reactive system was evaluated as a targeting agent for pretargeted imaging in tumor-bearing mice. After the setup was optimized, sufficient tumor-to-background ratios were achieved as early as 2 h after administration of the tetrazine imaging agent, which further improved at 22 h, enabling clear visualization of CT-26 tumors. These findings show the potential of PeptoBrushes to be used as a pretargeting agent when an optimized dose of polymer is used.

Fe-catalyzed Decarbonylative Alkylative Spirocyclization of N-Arylcinnamamides: Access to Alkylated 1-Azaspirocyclohexadienones

For the convenient introduction of simple linear/branched alkyl groups into biologically important azaspirocyclohexadienones, a practical Fe-catalyzed decarbonylative cascade spiro-cyclization of N-aryl cinnamamides with aliphatic aldehydes to provide alkylated 1-azaspiro-cyclohexadienones was developed. Aliphatic aldehydes were oxidative decarbonylated into primary, secondary and tertiary alkyl radicals conveniently and allows for the subsequent cascade construction of dual C(sp³)-C(sp³) and C=O bonds via radical addition, spirocyclization and oxidation sequence.

Synthesis of Novel Structural Hybrids between Aza-Heterocycles and Azelaic Acid Moiety with a Specific Activity on Osteosarcoma Cells

Nine compounds bearing pyridinyl (or piperidinyl, benzimidazolyl, benzotriazolyl) groups bound to an azelayl moiety through an amide bond were synthesized. The structural analogy with some histone deacetylase inhibitors inspired their syntheses, seeking new selective histone deacetylase inhibitors (HDACi). The azelayl moiety recalls part of 9-hydroxystearic acid, a cellular lipid showing antiproliferative activity toward cancer cells with HDAC as a molecular target. Azelayl derivatives bound to a benzothiazolyl moiety further proved to be active as HDACi. The novel compounds were tested on a panel of both normal and tumor cell lines. Non-specific induction of cytotoxicity was observed in the normal cell line, while three of them induced a biological effect only on the osteosarcoma (U2OS) cell line. One of them induced a change in nuclear shape and size. Cell-cycle alterations are associated with post-transcriptional modification of both H2/H3 and H4 histones. In line with recent studies, revealing unexpected HDAC7 function in osteoclasts, molecular docking studies on the active molecules predicted their proneness to interact with HDAC7. By reducing side effects associated with the action of the first-generation inhibitors, the herein reported compounds, thus, sound promising as selective HDACi.

Controlled Release of Spirotetramat Using Starch-Chitosan-Alginate-Encapsulation

This study was intended to develop an environment-friendly controlled release system for spirotetramat in an alginate matrix. Four formulations, starch-chitosan-calcium alginate (SCCA), starch-calcium alginate (SCA), chitosan-calcium alginate (CCA), and calcium alginate (CA) complex gel beads, were prepared by the extrusion-exogenous gelation method. The properties of the formulations were studied. The results showed that the release behaviors of the formulations in water could be well described by the logistic model, and the release occurred through Fickian diffusion. Among the four formulations, SCCA showed the highest entrapment efficiency, drug loading and the slowest release rate. Degradation studies revealed that the SCCA formulation exhibited an obvious slower degradation rate of spirotetramat in soils than the commercially available formulation. The estimated half-life of the SCCA formulation was 2.31, 3.25, and 4.51 days in waterloggogenic paddy soil, purplish soil, and montmorillonite, respectively, when the soils were moistened to 60% of its dry weight. This study provided a possible approach to prolong the duration of spirotetramat and to reduce environmental contamination.

Catalytic Enantio- and Diastereoselective Cyclopropanation of 2-Azadienes for the Synthesis of Aminocyclopropanes Bearing Quaternary Carbon Stereogenic Centers

We report the catalytic enantio- and diastereoselective preparation of aminocyclopropanes by the cyclopropanation of terminal and (Z)-internal 2-azadienes with donor/acceptor carbenes derived from α-diazoesters. The resulting cyclopropanes bear quaternary carbon stereogenic centers vicinal to the amino-substituted carbon and are formed as a single diastereomer in up to 99:1 er and 97% yield with 0.5 mol % of Rh2(DOSP)4 and only 1.5 equiv of the diazo reagent. Transformations with internal azadienes afford cyclopropanes with three contiguous stereogenic centers.

Phosphine-Catalyzed α-Umpolung-Aldol Reaction for the Synthesis of Benzo[ b]azapin-3-ones

A novel phosphine-catalyzed intermolecular cyclization between 2-sulfonamidobenzaldehyes and ynones is reported. This methodology serves as a conduit for the construction of benzo[ b]azepin-3-ones in good to excellent yields under mild conditions. The resulting 2-benzylidene moieties are formed exclusively in the E-configuration. Mechanistically, this unusual annulation occurs through a phosphine-catalyzed α-umpolung addition, followed by an aldol reaction. One of the benzo[ b]azepin-3-one products was converted to the core structure of 3-amino-[ a]benzazepin-2-one-1-alkanoic acids, many of which function as angiotensin-converting enzyme inhibitors.

Guitarrins A-E and Aluminumguitarrin A: 5-Azaindoles from the Northwestern Pacific Marine Sponge Guitarra fimbriata

Guitarrins A-E (1-5), the first natural 5-azaindoles, and aluminumguitarrin A (1a), the first aluminum-containing compound from marine invertebrates, were isolated from the sponge Guitarra fimbriata. The structures of these compounds were established using detailed analysis of 1D and 2D NMR data, mass spectra, and X-ray analysis of 1 and 1a. Compound 3 was proved to be a natural inhibitor of alkaline phosphatase.

Deazaflavin Inhibitors of TDP2 with Cellular Activity Can Affect Etoposide Influx and/or Efflux

Tyrosyl DNA phosphodiesterase 2 (TDP2) facilitates the repair of topoisomerase II (TOP2)-linked DNA double-strand breaks and, as a consequence, is required for cellular resistance to TOP2 "poisons". Recently, a deazaflavin series of compounds were identified as potent inhibitors of TDP2, in vitro. Here, however, we show that while some deazaflavins can induce cellular sensitivity to the TOP2 poison etoposide, they do so independently of TDP2 status. Consistent with this, both the cellular level of etoposide-induced TOP2 cleavage complexes and the intracellular concentration of etoposide was increased by incubation with deazaflavin, suggesting an impact of these compounds on etoposide uptake/efflux. In addition, deazaflavin failed to increase the level of TOP2 cleavage complexes or sensitivity induced by m-AMSA, which is a different class of TOP2 poison to which TDP2-defective cells are also sensitive. In conclusion, while deazaflavins are potent inhibitors of TDP2 in vitro, their limited cell permeability and likely interference with etoposide influx/efflux limits their utility in cells.

Syntheses and evaluation of a homologous series of aza-vesamicol as improved radioiodine-labeled probes for sigma-1 receptor imaging

Sigma-1 receptor imaging probes for determining the expression levels are desirable for diagnoses of various diseases and companion diagnoses of therapeutic agents targeting the sigma-1 receptor. In this study, we aimed to develop probes with higher affinity for the sigma-1 receptor. For this purpose, we synthesized and evaluated compounds, namely, vesamicol derivatives, in which alkyl chains of varying chain length were introduced between a piperazine ring and a benzene ring. The binding affinity of the vesamicol derivatives for the sigma-1 receptor tended to increase depending on the length of the alkyl chain between the benzene ring and the piperazine ring. The sigma-1 receptor of 2-(4-(3-phenylpropyl)piperazin-1-yl)cyclohexan-1-ol (5) (Ki = 5.8 nM) exhibited the highest binding affinity; therefore, we introduced radioiodine into the benzene ring in 5. The radioiodine labeled probe [125I]2-(4-(3-(4-iodophenyl)propyl)piperazin-1-yl)cyclohexan-1-ol ([125I]10) showed high accumulation in the sigma-1 receptor expressing DU-145 cells both in vitro and in vivo. Co-injection of [125I]10 with an excess level of a sigma receptor ligand, haloperidol, resulted in a significant decrease in the tumor accumulation in vitro and in vivo, indicating sigma receptor-mediated tumor uptake. These results provide useful information for developing sigma-1 receptor imaging probes.

The influence of some promising fused azaisocytosine-containing congeners on zebrafish (Danio rerio) embryos/larvae and their antihaemolytic, antitumour and antiviral activities

The present study was aimed at broadening the profile of toxicity and biological activity of promising fused azaisocytosine-containing congeners (I-VI) possessing medical applicability and important pharmacokinetic properties. For this purpose, the in vivo zebrafish test was applied for evaluating embryotoxic effects of test compounds, whereas the ex vivo model of oxidatively-stressed rat erythrocytes was developed for assessing their antihaemolytic activities. Additionally, the MTT-based assays suitable for assessing cytotoxic and antiviral activities of I-VI were employed. The influence of compounds I-VI on zebrafish embryos/larvae was carefully investigated in relation to lack or presence of various substituents at the phenyl moiety. The least embryotoxic proved to be the parent compound (I) and its para-methyl (II) and ortho-chloro (III) derivatives. Simultaneously, they revealed the minimum embryotoxic concentrations higher than that of aciclovir, what makes them safer than this pharmaceutic. Moreover, most of test compounds showed protective effects (better or comparable to that of ascorbic acid) on oxidatively-stressed erythrocytes. All the investigated compounds were effective at inhibiting the growth of human solid tumours of pharynx (FaDu) and tongue (SCC-25). The majority of molecules showed good selectivity indices. The most selective proved to be II showing in normal Vero cells over a 5-fold and an almost 3-fold decreased cytotoxicity relative to that in tumour SCC-25 and FaDu cells, respectively. Additionally, a 3,4-dichloro derivative (VI) was shown to possess concentration-dependent inhibitory effects on the replication of Herpes simplex virus type 1 and simultaneously at active concentrations was found to be nontoxic for normal Vero cells.

ASR352, A potent anticancer agent: Synthesis, preliminary SAR, and biological activities against colorectal cancer bulk, 5-fluorouracil/oxaliplatin resistant and stem cells

Despite new agent development and short-term benefits in patients with colorectal cancer (CRC), metastatic CRC cure rates have not improved due to high rates of 5-fluorouracil (5-FU)/leucovorin/oxaliplatin (FOLFOX)-resistance and a clinical therapeutic plateau. At the same time, this treatment regime leads to significant toxicity, cost, and patient inconvenience. Drug-resistance is linked to CRC stem cells, which are associated with the epidermal-to-mesenchymal transition (EMT) pathway. Thus, to optimally treat CRC, a therapy that can target the cell survival and EMT pathways in both CRC bulk and stem cell populations is critical. We recently identified a novel small molecule NSC30049 (7a) that is effective alone, and in combination potentiates 5-FU-mediated growth inhibition of CRC bulk, FOLFOX-resistant, and CRC stem cells both in vitro and in vivo models. In the present study, we report the synthesis and anti-CRC evaluation of several stable and effective 7a analogs. ASR352 (7b) was identified as one of the equipotent 7a analogs that inhibited the growth of CRC bulk cells, sensitized FOLFOX-resistant cells, and reduced the sphere formation capacity of CRC stem cells. It appears that the complex mechanism of cytotoxicity for 7b includes abrogation of 5-FU-induced the S phase, reduction of the phosphorylation of Chk1 at S317P, S345P and S296P, increased γH2AX staining, activation of caspase 3/PARP1 cleavage, and enhancement of Bax/Bcl2 ratio. Further 7b-mediated reduced phosphorylation of Chk1 was an indirect effect, since it did not inhibit Chk1 activity in an in vitro kinase assay. Our findings suggest that 7b as a single agent, or in combination with 5-FU can be developed as a therapeutic agent in CRC bulk, FOLFOX-resistant, and CRC stem cell populations for unmanageable metastatic CRC conditions.

Design, Synthesis, and Biological Evaluation of Polyaminocarboxylate Ligand-Based Theranostic Conjugates for Antibody-Targeted Cancer Therapy and Near-Infrared Optical Imaging

We report the design, synthesis, and evaluation of polyaminocarboxylate ligand-based antibody conjugates for potential application in targeted cancer therapy and near-infrared (NIR) fluorescence imaging. We synthesized a new polyaminocarboxylate chelate (CAB-NE3TA) as a potential anticancer agent. CAB-NE3TA displayed potent inhibitory activities against various cancer cell lines. We then designed a multifunctional theranostic platform (CAB-NE3TA-PAN-IR800) constructed on an epidermal growth factor receptor (EGFR)-targeted antibody (panitumumab, PAN) labeled with a NIR fluorescent dye. We also built the first atomistic model of the EGFR-PAN complex and loaded it with the cytotoxic CAB-NE3TA and the NIR dye. The therapeutic (CAB-NE3TA-PAN) and theranostic (CAB-NE3TA-PAN-IR800) conjugates were evaluated using an EGFR-positive A431 (human skin cancer) cell xenograft mouse model. Biodistribution studies using NIR fluorescence imaging demonstrated that the CAB-NE3TA-PAN labeled with the IR800 dye selectively targeted the A431 tumors in mice and resulted in prolonged retention in the tumor tissue and displayed excellent clearance in blood and normal organs. The therapeutic conjugate was capable of significantly inhibiting tumor growth, leading to nearly complete disappearance of tumors in the mice. The results of our pilot in vivo studies support further evaluation of the novel ligand-based therapeutic and theranostic conjugates for targeted iron chelation cancer therapy and imaging applications.

Substrate-Induced Self-Assembly of Cooperative Catalysts

Dissipative self-assembly processes in nature rely on chemical fuels that activate proteins for assembly through the formation of a noncovalent complex. The catalytic activity of the assemblies causes fuel degradation, resulting in the formation of an assembly in a high-energy, out-of-equilibrium state. Herein, we apply this concept to a synthetic system and demonstrate that a substrate can induce the formation of vesicular assemblies, which act as cooperative catalysts for cleavage of the same substrate.

Adsorption and Desorption Behaviors of Spirotetramat in Various Soils and Its Interaction Mechanism

Spirotetramat is a pesticide with bidirectional systemicity and can effectively control pests by inhibiting the biosynthesis of fatty acids. In this study, adsorption and desorption behaviors of spirotetramat in six soils and its interaction mechanism were studied using the batch equilibrium method and infrared radiation. The results showed that the adsorption and desorption behaviors of spirotetramat conformed to the Freundlich isotherm model. The values of adsorption capacities K_F-ads ranged from 2.11 to 12.40, and the values of desorption capacities K_F-des varied from 2.97 to 32.90. From the hysteresis coefficient, spirotetramat was easily desorbed from the test soils. The adsorption capacity of the soil to spirotetramat enhanced with an increasing temperature. Moreover, the changes in pH values and exogenous addition of humic acid and surfactant could also affect soil adsorption capacity, but for desorption, there was no correlation.

Enhancement of Spirotetramat Transfer in Cucumber Plant Using Mesoporous Silica Nanoparticles as Carriers

Pesticides will be used for a long period of time, and their use may cause environmental contamination and adverse effects on human health. The aim of this study was to improve the utilization rate of pesticides and reduce the risk to the environment using mesoporous silica nanoparticles (MSNs) as carriers. Compared to the conventional formulation, spirotetramat-loading MSNs improved deposition, uptake, and translocation performance in cucumber plants. MSNs may hold spirotetramat in their mesoporous structure and prevent its degradation in plants. The final residue of spirotetramat and its metabolites demonstrated that spirotetramat-loading MSNs had low risk to the edible parts of plants under foliar application. This study added our knowledge of MSNs controlling pesticide release and transfer in plant.

Secondary Photocrosslinking of Click Hydrogels To Probe Myoblast Mechanotransduction in Three Dimensions

Muscle cells sense the mechanical properties of their microenvironment, and these properties can change in response to injury or disease. Hydrogels with dynamic material properties can be used to study the effect of such varying mechanical signals. Here, we report the ability of azadibenzocyclooctyne to undergo a cytocompatible, photoinitiated crosslinking reaction. This reaction is exploited as a strategy for on-demand stiffening of three-dimensional cell scaffolds formed through an initial strain-promoted azide-alkyne cycloaddition. Myoblasts encapsulated in these networks respond to increased matrix stiffness through decreased cell spreading and nuclear localization of Yes-associated protein 1 (YAP). However, when the photocrosslinking reaction is delayed to allow cell spreading, elongated myoblasts display increased YAP nuclear localization.

Environmental behaviors of spirotetramat in water

Spirotetramat is a pesticide with bidirectional systemicity in both xylem and phloem. Currently, researches show that spirotetramat has definite toxicity to aquatic organism. This paper aims to study the environmental behaviors of spirotetramat in water, in the hope of providing guidance for security evaluation of spirotetramat. The researches in this paper showed that under lighting condition, the half-life period of spirotetramat in water was 13.59 days. In water, spirotetramat could be degraded into B-enol and B-keto. As seen from the residual concentrations of two products, B-enol was the dominant degradation product. Under different temperatures, the hydrolysis products of spirotetramat remain B-enol and B-keto. The temperature has little effect on the residual concentration of spirotetramat in water. The residual concentration of B-enol in water gradually increased with the extension of time but B-keto had no significant change. In the buffer solution of different pH values, the degradation rate of spirotetramat was significantly enhanced with the increase of solution pH value. The hydrolysis products of spirotetramat in buffer solution of different pH values were still B-enol and B-keto, and pH exerted certain influence on the residual concentration of B-enol in water. The hydrolysis conversion of spirotetramat has theoretical and practical significance for the safe and reasonable usage of it, as well as for the further evaluation of spirotetramat's ecological risk in water.

A Self-Assembled Biocompatible Nanoplatform for Multimodal MR/Fluorescence Imaging Assisted Photothermal Therapy and Prognosis Analysis

The need for better imaging assisted cancer therapy calls for new biocompatible agents with excellent imaging and therapeutic capabilities. This study successfully fabricates albumin-cooperated human serum albumin (HSA)-GGD-ICG nanoparticles (NPs), which are comprised of a magnetic resonance (MR) contrast agent, glycyrrhetinic-acid-modified gadolinium (III)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (GGD), and a fluorescence (FL) dye, indocyanine green (ICG), for multimodal MR/FL imaging assisted cancer therapy. These HSA-GGD-ICG NPs with excellent biocompatibility are stable under physiological conditions, and exhibit enhanced T₁ contrast capability and improved fluorescence imaging capacity. In vitro experiments reveal an apparent effect of the NPs in killing tumor cells under low laser irradiation, due to the enhanced photothermal conversion efficiency (≈85.1%). Importantly, multimodal MR/FL imaging clearly shows the in vivo behaviors and the efficiency of tumor accumulation of HSA-GGD-ICG NPs, as confirmed by a pharmacokinetic study. With the guidance of multimodal imaging, photothermal therapy is subsequently conducted, which demonstrates again high photothermal conversion capability for eliminating tumors without relapse. Notably, real-time monitoring of tumor ablation for prognosis and therapy evaluation is also achieved by MR imaging. This strategy of constructing nanoplatforms through albumin-mediated methods is both convenient and efficient, which would enlighten the design of multimodal imaging assisted cancer therapy for potential clinical translation.

The State of the Art in Azaborine Chemistry: New Synthetic Methods and Applications

Boron-nitrogen heteroarenes hold great promise for practical application in many areas of chemistry. Enduring interest in realizing this potential has in turn driven perennial innovation with respect to these compounds' synthesis. This Perspective discusses in detail the most recent advances in methods pertaining to the preparation of BN-isosteres of benzene, naphthalene, and their derivatives. Additional focus is placed on the progress enabled by these syntheses toward functional utility of such BN-heterocycles in biochemistry and pharmacology, materials science, and transition-metal-based catalysis. The prospects for future research efforts in these and related fields are also assessed.

Stereodivergent Allylation of Azaaryl Acetamides and Acetates by Synergistic Iridium and Copper Catalysis

We report stereodivergent allylic substitution reactions of allylic esters with prochiral enolates derived from azaaryl acetamides and acetates to form products from addition of the enolates at the most substituted carbon of an allyl moiety with two catalysts, a chiral metallacyclic iridium complex and a chiral bisphosphine-ligated copper(I) complex, which individually control the configuration of the electrophilic and nucleophilic carbon atoms, respectively. By simple permutations of enantiomers of the two catalysts, all four stereoisomers of products containing two stereogenic centers were synthesized individually with high diastereoselectivity and enantioselectivity. A variety of azaaryl acetamides and acetates bearing pyridyl, benzothiazolyl, benzoxazolyl, pyrazinyl, quinolinyl and isoquinolinyl moieties were all found to be suitable for this transformation.

New insights into structure-activity relationship of ipomoeassin F from its bioisosteric 5-oxa/aza analogues

Ipomoeassin F, a plant-derived macrolide, exhibited single-digit nanomolar growth inhibition activity against many cancer cell lines. In this report, a series of 5-oxa/aza analogues was prepared and screened for cytotoxicity. Replacement of 5-CH2 with O/NH simplified the synthesis and led to only a small activity loss. N-methylation almost completely restored the potency. Further studies with additional 5-oxa analogues suggested, for the first time, that size and flexibility of the ring also significantly influence the bioactivity of ipomoeassin F.

2-Azadienes as Reagents for Preparing Chiral Amines: Synthesis of 1,2-Amino Tertiary Alcohols by Cu-Catalyzed Enantioselective Reductive Couplings with Ketones

We introduce a new strategy for synthesis of chiral amines: couplings of α-aminoalkyl nucleophiles generated by enantioselective migratory insertion of 2-azadienes to a Cu-H. In this report, we demonstrate its application in catalytic reductive coupling of 2-azadienes and ketones to furnish 1,2-amino tertiary alcohols with vicinal stereogenic centers.

Dual-Nuclide Radiopharmaceuticals for Positron Emission Tomography Based Dosimetry in Radiotherapy

Improvement of the accuracy of dosimetry in radionuclide therapy has the potential to increase patient safety and therapeutic outcomes. Although positron emission tomography (PET) is ideally suited for acquisition of dosimetric data because PET is inherently quantitative and offers high sensitivity and spatial resolution, it is not directly applicable for this purpose because common therapeutic radionuclides lack the necessary positron emission. This work reports on the synthesis of dual-nuclide labeled radiopharmaceuticals with therapeutic and PET functionality, which are based on common and widely available metal radionuclides. Dual-chelator conjugates, featuring interlinked cyclen- and triazacyclononane-based polyphosphinates DOTPI and TRAP, allow for strictly regioselective complexation of therapeutic (e.g., 177 Lu, 90 Y, or 213 Bi) and PET (e.g., 68 Ga) radiometals in the same molecular framework by exploiting the orthogonal metal ion selectivity of these chelators (DOTPI: large cations, such as lanthanide(III) ions; TRAP: small trivalent ions, such as GaIII ). Such DOTPI-TRAP conjugates were decorated with 3 Gly-urea-Lys (KuE) motifs for targeting prostate-specific membrane antigen (PSMA), employing Cu-catalyzed (CuAAC) as well as strain-promoted (SPAAC) click chemistry. These were labeled with 177 Lu or 213 Bi and 68 Ga and used for in vivo imaging of LNCaP (human prostate carcinoma) tumor xenografts in SCID mice by PET, thus proving practical applicability of the concept.

Identification of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane-dithiocarbamate-nitrostyrene hybrid as potent antiproliferative and apoptotic inducing agent against cervical cancer cell lines

The present study seeks to describe the design and synthesis of six new Michael adducts of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane-dithiocarbamate with nitrostyrenes and their in vitro antiproliferative activity against human cervical cancer cell lines [HeLa (HPV 18 positive), CaSki (HPV 16 positive) and ViBo (HPV negative) cervical cancer cell lines]. Virtual screening of the physicochemical properties of all compounds have also been presented. All the compounds exploited significant antiproliferative activity on the three cervical cancer cell lines. Compound 8a was found to be most potent, displaying in vitro antiproliferative activity against HeLa, CaSki and ViBo cervical cancer cell lines superior to Cisplatin and Paclitaxel with IC₅₀ values 0.99 ± 0.007, 2.36 ± 0.016 and 0.73 ± 0.002 μM respectively. In addition, compound 8a did not trigger the necrosis cell death to the test cancer cell lines. Further mechanistic study revealed that compound 8a could inhibit the cancer cell proliferation by inducing apoptosis through caspase-3 activation. Moreover, cell cycle analysis indicated that compound 8a could arrest the cell cycle at the G1 phase for HeLa and CaSki cancer cells. At the predetermined IC₅₀ values on cancer cells, compound 8a did not induce any necrotic (cytotoxic) death to the normal human lymphocytes. In the present design, (1S,4S)-2,5-diazabicyclo[2.2.1]heptane system was found to be superior than the piperazine counterpart 11.

Adenosine: Synthetic Methods of Its Derivatives and Antitumor Activity

Since 1929, several researchers have conducted studies in relation to the nucleoside of adenosine (1) mainly distribution identifying, characterizing their biological importance and synthetic chemistry to which this type of molecule has been subjected to obtain multiple of its derivatives. The receptors that interact with adenosine and its derivatives, called purinergic receptors, are classified as A1, A2A, A2B and A3. In the presence of agonists and antagonists, these receptors are involved in various physiological processes and diseases. This review describes and compares some of the synthetic methods that have been developed over the last 30 years for obtaining some adenosine derivatives, classified according to substitution processes, complexation, mating and conjugation. Finally, we mention that although the concentrations of these nucleosides are low in normal tissues, they can increase rapidly in pathophysiological conditions such as hypoxia, ischemia, inflammation, trauma and cancer. In particular, the evaluation of adenosine derivatives as adjunctive therapy promises to have a significant impact on the treatment of certain cancers, although the transfer of these results to clinical practice requires a deeper understanding of how adenosine regulates the process of tumorigenesis.

Understanding and Interrupting the Fischer Azaindolization Reaction

Experimental and computational studies pertaining to the Fischer azaindolization reaction are reported. These studies explain why pyridylhydrazines are poorly reactive in Fischer indolization reactions, in addition to the origin of hydrazine substituent effects. Additionally, an interrupted variant of Fischer azaindolization methodology is disclosed, which provides a synthetic entryway into fused azaindoline scaffolds.

Copper-Catalyzed Alkene Aminoazidation as a Rapid Entry to 1,2-Diamines and Installation of an Azide Reporter onto Azahetereocycles

A copper-catalyzed aminoazidation of unactivated alkenes is achieved for the synthesis of versatile unsymmetrical 1,2-diamine derivatives. This transformation offers an effective approach to installing an amide and an azide from two diffenent amino precursors onto both terminal and internal alkenes, with remarkable regio- and stereoselectivity. Mechanistic studies show that this diamination reaction proceeds via a nucleophilic amino cyclization followed by an intermolecular C-N bond formation using electrophilic azidoiodinane. This pathway differs from previous azidoiodinane-initiated alkene functionalization, suggesting new reactivity of azidoiodinane. Furthermore, this aminoazidation reaction provides an efficient strategy to introduce azide, one of the most useful chemical reporters, onto a broad range of bioactive azaheterocycles, offering new opportunities in bioorthogonal chemistry and biological studies. Rapid syntheses of 5-HT2C agonist, (-)-enduracididine and azido-cholesterol derivatives demonstrate broad applications of this method in organic synthesis, medicinal chemistry, and chemical biology.